Shoe collar height effect on athletic performance,ankle joint kinematics and kinetics during unanticipated maximum-effort side-cutting performance

Side-step cutting manoeuvres comprise the coordination between planting and non-planting legs. Increased shoe collar height is expected to influence ankle biomechanics of both legs and possibly respective cutting performance. This study examined the shoe collar height effect on kinematics and kinetics of planting and non-planting legs during an unanticipated side-step cutting. Fifteen university basketball players performed maximum-effort side-step cutting to the left 45° direction or a straight ahead run in response to a random light signal. Seven successful cutting trials were collected for each condition. Athletic performance, ground reaction force, ankle kinematics and kinetics of both legs were analysed using paired t-tests. Results indicated that high-collar shoes resulted in less ankle inversion and external rotation during initial contact for the planting leg. The high-collar shoes also exhibited a smaller ankle range of motion in the sagittal and transverse planes for both legs, respectively. However, no collar effect was found for ankle moments and performance indicators including cutting performance time, ground contact time, propulsion ground reaction forces and impulses. These findings indicated that high-collar shoes altered ankle positioning and restricted ankle joint freedom movements in both legs, while no negative effect was found for athletic cutting performance.     

Urine specific gravity as an indicator of dehydration in Olympic combat sport athletes; considerations for research and practice

Urine specific gravity (U_SG) is the most commonly reported biochemical marker used in research and applied settings to detect fluid deficits in athletes, including those participating in combat sports. Despite the popularity of its use, there has been a growing debate regarding the diagnostic accuracy and the applicability of U_SG in characterizing whole-body fluid status and fluctuations. Moreover, recent investigations report universally high prevalence of hypohydration (～90%) via U_SG assessment in combat sport athletes, often in spite of stable body-mass. Given the widespread use in both research and practice, and its use in a regulatory sense as a ‘hydration test’ in combat sports as a means to detect dehydration at the time of weigh-in; understanding the limitations and applicability of U_SG assessment is of paramount importance. Inconsistencies in findings of U_SG readings, possibly as a consequence of diverse methodological research approaches and/or overlooked confounding factors, preclude a conclusive position stand within current combat sports research and practice. Thus the primary aim of this paper is to critically review the literature regarding U_SG assessment of hydration status in combat sports research and practice. When taken on balance, the existing literature suggests: the use of laboratory derived benchmarks in applied settings, inconsistent sampling methodologies, the incomplete picture of how various confounding factors affect end-point readings, and the still poorly understood potential of renal adaptation to dehydration in combat athletes; make the utility of hydration assessment via U_SG measurement quite problematic, particularly when diet and training is not controlled.     

提高全自动圆材校直切断机送料精度的方法

主要论述了从德国引进的全自动圆材校直切断机送料系统精度存在的不足以及提高送料精度的方法,结果表明：送料机构改进后使滑块位移误差减小,送料精度由0．10mm-0．31mm提高到0．07mm-0．115mm,并能够稳定精度。     

葡萄硬枝扦插对基质的优选

运用薄膜冷床对砂土、锯木屑、壤土和粘壤土四种不同处理进行葡萄硬枝扦插试验,选出砂土为最好的培养基质.     

薄壁零件数控加工工艺实现关键技术及应用研究

本文着重研究了薄壁零件数控加工工艺的关键技术。根据材料力学原理,求解薄壁零件弹塑性变形临界条件。在保证薄壁零件加工切削力小于极限载荷的条件下,采用最大切削量对其加工,从而实现薄壁零件的高效加工。     

中国剪纸艺术的历史沿革

剪纸是我国民间广泛流传的一种艺术样式，其发展历史由来已久，反映出中国人自古就懂得“虚实相生，虚实互补”的造型原则。剪纸艺术在不同的历史时期有其不同的发展状况，它与当时的社会紧密联系，根植于“民间”这片沃土，并且茁壮成长。     

木材切削原理与刀具课程教学改革

根据普通高校木材科学与工程专业的培养目标和要求,分析了课程教学过程中存在的问题.对教学内容进行调整更新,增加实践教学内容,丰富教学方法,将抽象知识形象化,有效提高学生对木材切削原理及刀具的认知能力,激发学生学习的主动性和积极性,提高教学效果.     

鄂城花样工会成立史实考辨

花样剪纸工艺是我国非物质文化遗产的重要组成部分,近代的鄂城花样剪纸的同业工会组织是目前我国历史上罕见的民间社团组织,关于该组织成立的具体时间问题,因此前所见文章资料叙说的重重矛盾而变得使人难以信服.该文通过新发现的花样工会原始材料,对鄂城花样工会成立的时间进行了推断,对其发展的脉络进行了简单的梳理.     

数控车（铣）床试切法对刀探究

在数控加工中,工件坐标系确定后,还要确定刀具的刀位点在工件坐标系中的位置,即常说的对刀问题。数控机床上,目前,常用的对刀方法为手动试切对刀。而对刀是数控加工中最主要的操作以及最重要的技能,在可稳定的条件中,提高加工中的对刀精度是零件生产加工中的重要环节。本次研究中从数控车（铣）床的对刀原理相关技术以及对刀方法来阐述与探究,对刀选择中使用广州数控980T系统来举例提出相关论述。     

机械式密封在采煤机截割部行星机构上的应用

文章叙述了传统浮环密封的主要缺点,介绍了机械式密封的主要优点以及在安装、包装、运输、贮藏时的注意事项。